1. Field of the Invention
The present invention relates to multiple light source illuminating devices intended to replace incandescent, fluorescent and HID luminaries in general and specialty lighting applications.
2. Background and Description of the Prior Art
Prior art lighting practice utilizes an apparatus termed a luminaire or Lighting Fixture to provide illumination to indoor and outdoor living spaces, vehicles machinery etc for the performance of various visual tasks. A luminaire provides features other than just light which may include light distribution, shielding, man-machine-interfaces such as on/off switches, connection to power mains, apparatus for affixation to construction elements and aesthetics. A typical prior art luminaire is comprised of: a replaceable lamp, a lamp holder, wiring, optical control elements such as a reflectors and refractors, fasteners and brackets. In addition if the lamp has a negative resistance characteristic, then the luminaire includes power control elements such as a ballast. If a light control system is employed also included are elements including relays, logic controllers and communication devices which may be part of an electronic ballast design. All of these elements packaged together constitute a luminaire. In typical present day luminaire (lighting fixture) practice, a lamp with a mostly radially uniform spatial light distribution is placed within an optical assembly consisting of a reflector and or refractor for the purpose of having the light exit the luminaire in the desired direction and preferred distribution pattern. This is a process that involves cost and inefficiencies in redirecting the light.
Recently solid-state light sources have evolved from indicator lamps into illumination sources. The present art approach is to package these new lamp types into luminaires of the old lamp type with some minor adjustments. This was the case when fluorescents replaced incandescents and when HID replaced fluorescents. The question arises, is this really the best solution as far as functionality and construction are concerned. The question is especially cogent when the fact that solid state light sources are electronic devices with high reliability, long lifetimes and are capable of rapid change over a very wide operating range.
Examples of the inflexible prior-art approach based on today's designs include: lighting is often provided in rooms where daylight contributes significantly to the overall lighting level or in areas near the window but the lighting system is not flexible enough spatially to take advantage of the daylight contribution and reduce power; or the lighting is always on at maximum power irrespective of whether or not there is activity in the room to justify the lighting level.
Even when external dimming controls are provided to the lighting fixture, the color quality of the lighting is deleteriously affected. At a lower lighting level a warmer color temperature is generally required and the luminaire lamp color is not adjustable.
Lighting systems are generally based around a lamp source and lighting application. When a new lamp source arrives generally they are placed into present-day lighting luminaire designs which are not optimal for the new light source. LEDs are a light source which have a number of advantages due to relatively long life expectancy. In the future it is also expected that LEDs will have conversion efficiencies equivalent to those of discharge lamps. Presently however, the high cost of lumen per watt appears to make LEDs uneconomical for most lighting applications. A few applications of which step, stairwell, pathway and emergency lighting are examples require low lighting levels to begin with and thus present at this time a feasible application. An LED light source is well adapted to a number of additional applications. Very often in these additional applications the areas over which the lighting is to be provided are large and bringing electric power to the luminaire is a significant safety and cost consideration. An inherently low voltage light source such as an LED is suitable for use with safe 12 or 24 volt of a distributed power system with low current demands. The control of the light distribution, especially the beam cut-off necessary at low light levels to prevent discomfort, is well suited to the high directionality of the small LED light source. Maintenance of prior-art luminaires in outdoor applications and the requirement for watertight resealing, increases fixture cost and complexity. Robustness of luminaires is another requirement as they located on ground level endangered by passersby contact or vandalism.
In prior art lighting fixture construction, the lamp, reflector, socket and ballast are separate units. Foremost, the lamp must be replaceable and thus access provided, because the lamp lifetime is less than other components in the fixture. The reflector is large, to envelope the light source and provide ray control, and is manufactured of special, highly reflective, material. The power-conditioning device such as a core and coil ballast or more recently electronic power transistor components differs again from the glass lamp, reflector and fixture material. The dissimilarity of the manufacturing technologies, operating lifetimes and materials results in a multi-component fixture assembly held together by fasteners which don't lend themselves to mass production and the luminaires are not factory sealed for life.
In order to clarify the intent of the present invention and its dissimilar aspects from prior art, a nomenclature system is established.
Lamp: A lamp, other than a reflector lamp, is generally a device that generates light radially from the source. Due to the physics involved in the light generation process, it is difficult at the source to gain control of the spatial light propagation. A reflector lamp will partially control the emitted light which hits the reflector, but will not control the remaining light emanating from the filament or discharge tube. A lamp other than a solid-state lamp will generally produce light over a wide range of spectrum. The overall color is a function of the physics involved in the generation of the different photon energies. While some lamps spectra are closer to sunlight and have a good color rendering in relation thereto, other lamps such as low-pressure sodium are highly monochromatic with a yellow-orange appearance. A color temperature in degrees Kelvin based on the color of an incandescent filament is used to describe a lamp. An incandescent lamp color will be termed “warm” at 2000 Kelvin and a Metal Halide “cool” at 4000K. In general, there is no ability to affect the color over the intensity level even where dimming is afforded. A lamp is also intended to be a replaceable element. Lamps are constructed according to universal standards which allow for the substitution of lamps by other manufacturers. Prior-art lamps are thus provided with bulky bases which fit into bulky sockets and do not lend themselves to being permanently wired into printed circuit boards or bonded onto electronic chips.
Luminaire: A Lighting Fixture or luminaire (the terms are used interchangeably) is a device which is constructed around the lamp to provide lighting specific to the application including non-lighting considerations such as aesthetics, safety etc. Some LF designs are primarily based on aesthetics while others are based on tailoring the lumen output such that the lighting fixture output meets the visual task at hand. Between these two extremes there are many possible designs, with maintenance, fixture cost, hazardous and rough service location considerations also playing a role. This is essentially why the industry produces so many different types of luminaires. One type for high industrial building ceilings known as high-bay lighting, another for office lighting and a third for roadway lighting and a fourth for illuminating corridors. Each fixture has its photometric distribution characteristics, that is, how many candela at what angle are exiting from the luminaire. Other luminaire considerations include keeping the lighting from causing discomfort glare or from being a source of veiling reflections. The purely technical goal is to get the required amount of light at the work surfaces where visual tasks are carried out by man, animals, plants and machines. A LF has a longer life than the lamp, and the lamp is meant to be replaceable within the fixture. A luminaire is wired directly to the electrical mains while a lamp due to its need to be replaced has a base which fits into a socket by way of which the lamp receives its power. Prior art solid-state lamp assemblies are considered lamps, as they have no provision for being connected to the mains. A luminaire has apparatus whereby it is attached to the building structure while a lamp is mechanically affixed to the lamp holder or socket. Another aspect of distinction is, that in general, correct lighting practice principles are used to guide in the design of a LF while a lamp is “bare” and is expected to have reflectors, refractors, shades and louvers to prevent glare and redirect its rays to increase light utilization.
Digital: The term digital used herein in refers to the luminaire concept as espoused by teachings of this invention and is loosely defined in parallel to the fine control associated with digital equipment. The multiple light sources of specific characteristics provide quanta of power and spectrum which are smoothly added or detracted to generate a changed lighting effect. The digital aspect arises from the sufficient progression of values, varying by minute degrees to produce a continuum so as be non-discernable or irrelevant to the user. The added controllability is realized by breaking up the light-production, into discrete, specifically aimable, and dimmable elements which can be addressed by control electronics for the purpose of affecting the intensity, spectrum and spatial distribution of spectrum and of intensity of the illumination provided by the luminaire of the present invention.
The overall combination of control capability and discrete light sources yields a digital lighting fixture. The terminology “digital” as used herein also refers to the discrete nature of the multiple LED lamps provided in the luminaire, whereby, “digital” control results from the individual control of the discrete, i.e., “digital” lighting elements, the LEDs, in the luminaire.
Correct lighting practice: A bare incandescent lamp illuminating a room is arbitrarily termed poor lighting practice. The bare light bulb hooked up to the electric power via a light switch, causes glare, wastes light, delivering the light to useless areas, has no provision for dimming and is energy inefficient. The Illuminating Engineering Society of North America (IESNA) as well as other professional groups such as the International Association of Lighting Designers (IALD), have developed recommended lighting practices for specific applications in indoor and outdoor lighting. These recommendations and equations for implementing the recommendations can be found in the IESNA Lighting Handbook, 8th and/or 9th Editions (available from the Illuminating Engineering Society of North America 120 Wall St. Floor 17 New York, N.Y. 10005 included herein by reference. Factors in good lighting include lighting intensity levels which may be based on the age of the users of the light, the color rendering capacity of the light source, its color temperature, the non-production of glare, veiling reflections and energy efficiency amongst others. Recommendations for all aspects of lighting in terms of intensity, distribution, color temperature, color temperature as a function of light intensity and correct color rendering exist in the literature in terms of lighting applications that is the environment to be illuminated, in parameters such as lux for intensity, CRI for color rendering index and Visual Comfort Parameter (VCP) for glare. In recent years, the Unified Glare Rating (UGR) as recommended by the CIE has become widely accepted as a general formula for assessing glare. While the US may still use VCP ratings, all the lighting-practice engineering organizations worldwide have standards and recommended ratings for different activities. For example lighting levels of 500 lux and a UGR of 19 is recommended in offices while industrial areas intended for coarse work a UGR of 28 can tolerated. In good lighting practice, attention is given by lighting designers to the correct amount of uplight, that is light exiting from the luminaire towards the ceiling, which prevents a gloomy “dark cave” effect. Attention is also given to the cut-off angle of the luminaire, usually provided by shielding elements, such that high intensity rays are not emitted at an angle where they enter the occupant's eye during normal activity. A correctly designed luminaire for indoor lighting may provide 30% uplight and 70% downlight in the angles from the nadir 0 to 60 degrees and then again 135 to 170 degrees. A governing equation in lighting and used in “reverse luminaire design” of the present invention is the cosine law or Lambert's law, Equation 1:
  E  =                    I        ·        Cos            ⁢                          ⁢      θ              d      2      Where:                E=Illuminance in lux or footcandles,        I=Luminous intensity in candles,        D=Distance between the source and the point of calculation in meters or feet,        θ=Angle of light incidence with illuminated surface        
Another useful equation used in fixture analysis to avoid glare producing designs yields the level of discomfort on the DeBoer scale. The DeBoer rating scale (1-9) describes the level of discomfort where: 1=Unbearable, 3=Disturbing, 5=Just acceptable, 7=Satisfactory, and 9=Just noticeable. The allowable level is dependant on the application. A surgeon performing an operation may be very sensitive to glare while a chlorophyll producing plant is not. The equation to determine the rating is Equation 2:
  W  =      5    -                  2        ·        log            ⁢                        E          i                          3          ·                      10                          -              3                                ·                      [                          1              +                                                                    L                    a                                    0.04                                                      ]                    ·                      ϑ            i            0.46                              where:                W=glare sensation on a scale of 1 to 9,        La=adaptation luminance (cd/m2),        Ei=illumination directed at observer's eyes from the i-th source (lux),        φi=glare angle of the i-th source (minutes of arc).        
Using these equations and correct lighting practice covering preferred angles of lighting for visual tasks, it is possible to design from the specific application's illumination requirements the spatial light intensity distribution and yet avoid manufacturing a glare producing luminaire.
The present invention generally relates to an improved illuminator for use both in general and specialty lighting. The term general lighting includes use in living spaces such as lighting in industrial, commercial, residential and transportation vehicle applications. By specialty lighting we mean emergency lighting activated during power failures, fires or smoke accumulations in buildings, microscope, stage illuminators, billboard front-lighting, hazardous and difficult access location lighting, backlighting for signs, agricultural lighting etc.
Energy Efficiency and Costs. In an example to illustrate the advantages of an energy efficient lighting solution, the total cost of lighting a typical 300 foot by 300 foot retail facility at 1000 lux over a 10 year period using state of the art (2002) HID luminaires is assessed. Including equipment, installation and maintenance cost the total bill is over one million dollars. Approximately 80% of this is in energy costs. The commodity being purchased is lighting, the major lifecycle cost is electricity. To cut down on costs and also conserve energy it desirable to maximize the use of light generated. A Japanese survey of office luminaires (Japan Lighting Information Services-Seminar-Save Energy of Office Lighting-Loss of light in luminaire-.htm) shows LF efficiencies (light that exits the fixture vs. the light produced by the lamp) in an open office fluorescent luminaire without anti-glare louvers to be 84% while one equipped with louvers is only 52% efficient. The “utilization factor” (which equals the light flux which arrives at a work site (e.g. upper surface of a desk) divided by the sum of all light flux of the lamp) is 74% for an open fixture and only 50% for louvered version. This however, is still not what the customer is paying for. The customer is after the best lighting solution at minimal energy cost. Chances are, as experienced lighting designers know, that the light intensity, even in a good lighting design, is still not evenly distributed over the work surfaces. While care is taken in the lighting design computer runs not to fall below the minimum illumination intensity at any point in the room, there are non-trivial excesses at some points in the lighting layout design. This excess light, wasted energy as far as the customer is concerned, probably accounts for another 10% loss. While a fluorescent may be appear to be a superior and very efficient light source at 80 lumen per watt vs. 30 lumen per watt for LEDs this is not actually the case, in actuality 60% of the fluorescent LF's light is wasted. Thus, in terms of energy use, a properly designed LED luminaire can be, with the proper luminaire design of the present invention, as effective lumen per lumen as any discharge light source in illuminating living areas.
Expressed in terms of the above background and nomenclature, it is the goal of this disclosure to teach how to construct a luminaire which will radiate photons where needed, exactly in the correct amounts to accomplish visual tasks and/or create an atmosphere. The controlled radiation of light into a living space with a specific spatial intensity distribution also having optimal spectral characteristics for the seeing tasks at hand is provided by the present invention. Each visual task application has its own correct lighting solution with optimal light intensities, light color emanating at angles which will not cause glare that interferes with vision or causes discomfort. Tasks in living spaces vary with time so it is another objective of the present invention is to provide the optimal lighting solution in “real time” (at that specific moment in time).
As a light source of ever increasing choice, LEDs have been packaged in numerous forms and used in lighting applications. Special control circuits have been developed to take advantage of the variability offered by the new light source and are today being offered as a solution to specific applications. In general however the design process has not zeroed in on providing the correct lighting solution. A number of LED illumination devices create “white” light by combining two or more LEDs of various wavelengths. White LEDs are also made using phosphors. The goal has not been to vary this color spectrum in real time to coordinate with the usage of the living space. The term “white” light is loosely interpreted to cover a range of illuminating light acceptable to the user for that application. HPS's yellow light has even been called white by some and the term is exclusive only of almost monochromatic sources such as LEDs and LPS lamps. The terms light spectrum, spectra, spectrum, spectral and color are used to refer to the relative spectral power distribution of the light source.
A prior art LED light strip consists of circuitry including a plurality of LEDs mounted on a substrate and connected to electrical conductors. The circuitry is sometimes encased within a tube like, partially transparent protective sheathing and connected to a power source for selective LED illumination. Two examples of LED strip types are described in U.S. Pat. No. 5,130,909 to Gross, entitled Emergency Lighting Strip and U.S. Pat. No. 4,597,033 to Meggs et al., entitled Flexible Elongated Lighting System. Such strips are utilized in a variety of indoor and outdoor configurations such as emergency pathway markers, exit door indicators and ornamental lighting arrangements. The LEDs are being used as outline markers where the lighting strips are the object to be seen. It is not the purpose of the lighting strips to project light on other objects to make them visible. In other applications, where lighting distributed evenly along an area is required, these strips are placed at an edge. No attempt is made at obtaining an even illumination outward from the edge to the area perpendicular to the long dimension.
LED lamps and ballast systems can reduce maintenance costs due to an average rated life of 100,000 hours. This is five to eight times the typical service life of conventional fluorescent and metal halide lamps. The present system is especially well suited for applications where relamping is difficult or expensive.
U.S. Pat. No. 6,346,777 issued Feb. 12, 2002 to Kim teaches an illuminating lamp assembly. An LED lamp apparatus comprises a plurality of LED lamps including at least one LED chip mounted on a Printed Circuit Board (PCB), on which a driver circuit and/or a control circuit are provided in a printed circuit pattern to drive and/or control the LED chip. The device is independent of the lighting application and is simply a lamp not a lamp and fixture combination.
U.S. Pat. No. 5,018,290 issued May 28, 1991 to Kozek et al. Teaches an exit sign with a plurality of low voltage incandescent lamps mounted on a PCB to provide illumination from within a housing. There is no combination of different light source characteristics to build a new combined light source characteristic and this is a lamp replacement not a LF fit for general illumination.
U.S. Pat. No. 5,577,832 to Lodhie one of the originators of the use of LEDs for illumination, describes a multilayer LED assembly which is used as a replacement light for equipment used in manufacturing environments. On each layer of the multi-layer assembly, there are multiple LEDs which are mounted perpendicular to a base. The base is used to provide electrical and mechanical connection to a socket. The LED assembly may utilize multiple layers of LEDs, with each layer itself having multiple LEDs. The LEDs in each layer are mounted in a direction perpendicular to the base which results in light emanating in a direction perpendicular to the base. The LED assembly is used as a replacement lamp for equipment used in manufacturing environments. There is no attempt to match the light distribution to the task at hand.
U.S. Pat. No. 6,379,022 issued Apr. 30, 2002 to Amerson, et al. titled Auxiliary illuminating device having adjustable color temperature, describes an auxiliary illuminating device that has a least two preset ratios of light adjustable color temperature. The color temperature is adjusted by varying the light output at least two independently adjustable light sources. The light source is an array of at least 2 colors. The light source typically uses at least one set of LED's. The application specifically relates to use in producing correct lighting for photography but does not relate to general illumination so that its control equipment does not correlate the overall illuminance level to the color temperature over the range of illumination nor does its control equipment integrate the aiming function for correct light distribution. Essentially the auxiliary illuminating device is a lamp replacement for a photographic flash lamp.
U.S. Pat. No. 6,340,868, Illumination components, discloses a current control for an LED lighting assembly, where each current-controlled unit is uniquely addressable and capable of receiving illumination color information on a computer lighting network. The teachings of the above patent are incorporated herein by reference. Although this patent discloses how to construct controllable illumination light systems this patent does not relate to the concept of control within the parameters of accurate light distribution and correct lighting practice.
In U.S. Pat. No. 6,498,440 Stam, et al. incorporated herein by reference, describes a lamp assembly incorporating optical feedback to produce an illuminator assembly that is capable of utilizing a plurality of light sources to produce a desired resultant hue. The assembly includes a processor, a memory, a plurality of light sources and a detector. The memory is coupled to the processor and stores data and information. Each of the plurality of light sources are coupled to the processor and produce a different color. The processor is capable of independently controlling the intensity of each light source so as to produce a desired resultant hue. The detector is also coupled to the processor. The detector provides the processor with information which the processor utilizes in determining how to adjust the intensity of each of the light sources to provide the desired resultant hue.
In an earlier U.S. Pat. No. 5,803,579 titled: Illuminator assembly incorporating LEDs, by Turnbull, incorporated herein by reference, the different color LEDs light output is coincident in such a manner that this overlapped and mixed illumination forms a metameric white color and has sufficient intensity and color rendering qualities to be an effective illuminator. Electronic circuits for control of the independent light sources consist of microprocessor controlled adjustable current sources.
U.S. patent application Ser. No. 2,000,130,326 issued to Tamura et al., incorporated herein by reference, describes a lighting device that includes a plurality of LEDs arranged in an at least two-dimensionally dispersed manner; a transparent resin layer that covers the plurality of LEDs in an integrated form; a photo-detecting unit that detects an intensity of light emitted from the plurality of LEDs using a photodetector and a power supply circuit unit that controls driving of the plurality of LEDs based on a detection output from the photo-detecting unit. The purpose is to have a predetermined balance of light intensities of the colors according to an output detected as to each color by the photo-detecting unit. This device does not integrally cover the light distribution function within and does not correlate the lighting spectrum with the light intensity. It also does not provide a method to handle color shift over the lifetime of the illuminating device.
In U.S. Pat. No. 6,528,954 a light bulb is provided which may include a housing, an illumination source, disposed in the housing, and a processor, disposed in the housing, for controlling the illumination source. The housing may be configured to fit a conventional light fixture. The processor may control the intensity or the color of the illumination source. The housing may also house a transmitter and/or receiver. Although this device includes the desirable communications control aspect, this device does not relate to a multi-light source capability which allows for the smooth variation lighting and its even distribution.
In the prior-art approach, the LED manufacture and the power supply manufacture are separate units. Typically one power supply is good for a certain number of LEDs. This is similar to the historical lamp and ballast segregation that came about probably because one manufacturer was working with glass and the other with copper. Electronic light sources are semiconductor components as are the power supply components. A unique opportunity for integration exists in solid-state luminaire design which has not being taken advantage of.
In many energy conserving multi resident stairwell lighting systems the lights are typically activated by pressing a button in the hallway or in each apartment. This requires special wiring between the switches and the central controller. In many other stairwells and hallways the lighting is always left on wasting energy. With long life LED lamps, a low energy distributed lighting solution could always be on for orientation purposes and would only turn on to full output when activity levels require the lights turning on, using integral optoelectronic motion detectors.
A home lighting fixture is often left on at full power when really only lighting for orientation purposes is required. A light switch on the wall is provided and sometimes this has a dimmer option. An electronic power supply with programmable electronic controller with communication over a dedicated data line or alternately over the power line or alternately wireless is also possible in present art such as with the DALI (Digital Addressable Lighting Interface) protocol. With digital signals, power supplies become individually addressable compared to analog systems where only circuits are addressable. Additionally, DALI allows for bi-directional communication between the power supply and control. DALI also brings the capability of broadcast messaging to ballasts. With DALI or any other protocol much more than dimming can be effected. Control of spectrum, occupancy sensor controls and specific spatial intensity distributions can be modified. However, the present-day lamp or fixture is not designed to fully and efficiently take advantage of these new control capabilities.